What is the required fire-resistance rating (FRR) for heavy timber?

The required fire-resistance rating (FRR) for heavy timber is often established by building codes that take into consideration the material properties, usage, and fire safety measures for structures. Heavy timber can withstand fire for a significant amount of time due to its mass and slower rate of burning compared to other materials, which contributes to its ability to resist structural failure during a fire.

For heavy timber structures, a fire-resistance rating of 45 minutes is generally specified in many building codes, reflecting this material's performance characteristics. This rating allows for adequate time for occupants to evacuate and for fire-fighting efforts to initiate.

While other materials or construction types might have different requirements that exceed or fall short of this rating—such as light frame construction or concrete—heavy timber’s unique composition means it can provide a balance between safety and practicality in design. The 45-minute rating is in alignment with practices aimed at ensuring life safety and appropriate structural integrity in the event of a fire, particularly within certain building classifications.

Understanding this rating helps architects and builders make informed decisions in compliance with codes, enhancing the fire safety of their designs while effectively utilizing the benefits of heavy timber construction.